[Bug tree-optimization/121468] New: compiler hang at -Os on x86_64-linux-gnu

[zhendong.su at inf dot ethz.ch via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121468

            Bug ID: 121468
           Summary: compiler hang at -Os on x86_64-linux-gnu
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zhendong.su at inf dot ethz.ch
  Target Milestone: ---

Compiler Explorer: https://godbolt.org/z/5r3hc4Wb9

Note:
- It is a recent regression as it doesn't reproduce with 15.1 and earlier. 

[587] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/home/suz/suz-local/software/local/gcc-trunk/bin/../libexec/gcc/x86_64-pc-linux-gnu/16.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--enable-checking=yes --prefix=/local/suz-local/software/local/gcc-trunk
--enable-sanitizers --enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 16.0.0 20250807 (experimental) (GCC)
[588] %
[588] % timeout -s 9 10 gcctk -Os small.c
Killed
[589] %
[589] % cat small.c
int e, f, n;
static int a () { return e; }
void b () { while (a()); }
static int d () { return e; }
static void g (int h) {
  if (e)
  c:
    if (d())
      goto i;
  do {
    if (f)
      goto c;
    goto k;
  i:
    h = 2147483647;
  k:
    e = 2147483646;
    e = 6 + e;
    do {
      b ();
    } while (1784828957 / f + e + (808 + h) > 0);
  } while (1 % h);
}
void m () { g (-2); }
int main () {
  if (n)
    g (-1);
}